[ale] Update ifcfg-eth0 file from command line? (need to re-ip 50 servers)

[Jim Kinney]

sed -i -e 'edit #1' -e 'edit #2' ... -e 'edit #n’

The edits happen in sequence per line.

On Mar 19, 2017 12:46 AM, "Raj Wurttemberg" <rajaw at c64.us> wrote:

> Hey Phil,
>
> Can't say that I even knew that sed could do multiple replacements in one
> line. :)  (I've only been scripting with bash for about two years... I'm a
> noob) I just Googled it and came up with this...
>
> Is this kind of what you are talking about? (I've never used mktemp either)
>
> TMPIPCFG=$(mktemp /etc/sysconfig/network-scripts/tmpipcfg.XXXX)
> sed -i 's/IPADDR=.*/IPADDR=1.2.3.4/; s/BROADCAST=.*/BROADCAST=1.2.3.0/;
> s/GATEWAY=.*/GATEWAY=1.2.3.1/' $TMPIPCFG
> mv $TMPIPCFG /etc/sysconfig/network-scripts/ifcfg-eth0
>
> Learned something new tonight...
>
> Thanks!
> /Raj
>
> -----Original Message-----
> From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Phil
> Turmel
> Sent: Saturday, March 18, 2017 9:56 PM
> To: ale at ale.org
> Subject: Re: [ale] Update ifcfg-eth0 file from command line? (need to re-ip
> 50 servers)
>
> Aaaaahhhhhhgggg!
>
> Raj, Leam, y'all making me cringe with those procedures.  For pity's sake,
> use mktemp to safely make an empty temp file in the *same* folder, stream
> from the original to the temp file with *one* instance of sed, then 'mv'
> the
> temp file back over the original.  At no point will you have a partially
> configured network -- filesystems are required to guarantee that renaming
> over file atomically replaces it.  And at no point will you have an
> unsecure
> temp file exposed.
>
> Phil
>
> On 03/18/2017 09:03 PM, Raj Wurttemberg wrote:
> > Yeah, I was actually going to do a sed to just replace the old values and
> do most everything in one step:
> >
> > sed -i 's/IPADDR=.*/IPADDR=1.2.3.4/'
> > /etc/sysconfig/network-scripts/ifcfg-eth0 2> /dev/null sed -i
> > 's/BROADCAST=.*/BROADCAST=1.2.3.0/'
> > /etc/sysconfig/network-scripts/ifcfg-eth0 2> /dev/null sed -i
> > 's/GATEWAY=.*/GATEWAY=1.2.3.1/'
> > /etc/sysconfig/network-scripts/ifcfg-eth0 2> /dev/null
> >
> > haha... yes, I noticed a long time ago that the RHEL tries to use any
> file
> in the /etc/sysconfig/network-scripts directory! Doh!
> >
> > Thanks,
> > /Raj
> >
> >
> > -----Original Message-----
> > From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of
> > Leam Hall
> > Sent: Saturday, March 18, 2017 8:32 PM
> > To: Atlanta Linux Enthusiasts <ale at ale.org>
> > Subject: Re: [ale] Update ifcfg-eth0 file from command line? (need to
> > re-ip 50 servers)
> >
> > Untested, and I tend to do things in multiple steps.
> >
> > cp /etc/sysconfig/network-scripts/ifcfg-eth0 /tmp
> >
> > cat /tmp/ifcfg-eth0 | egrep -iv "ipaddr|broadcast|gateway" >
> > /etc/sysconfig/network-scripts/ifcfg-eth0
> >
> > echo "IPADDR=1.2.3.4" >> /etc/sysconfig/network-scripts/ifcfg-eth0
> > echo "BROADCAST=1.2.3.0" >> /etc/sysconfig/network-scripts/ifcfg-eth0
> > echo "GATEWAY=1.2.3.1" >> /etc/sysconfig/network-scripts/ifcfg-eth0
> >
> > service network restart
>
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